I posses several late or post-medieval bells or rather rumbler bells, purchased from metal detectorists. One in particular is an interesting find.
Here it is, front first and then back:
Note the goldish layer visible on the front. Imagine my surprise when I had access to an XRF and found that it was actually gold!
(I see no way in which it would have been worthwhile making up a fake like this and selling it on ebay for a single digit sum of money)
Now, the method of manufacture seemed a little tricky to work out, but was explained by this, the best wee guide to manufacturing methods that I have found so far:
About the only thing missing is that the casting of such bells would have likely been done into stone or bronze moulds.
Which means that either I need to carve another mould for casting such bells in their flat state, or do it by means of lost wax. The difficulty with both being that it is hard to get metal to go down into narrow places unless it is very hot, which is hard to do in my small furnace. As for making it take up the proper shape, I have anvils, and with enough practise can probably work something out. Which then makes me wonder if they made the bell take shape by beating it with a hammer. The example illustrated in that webpage certainly looks like the overlapping edge has been beaten, as does mine. Furthermore, perhaps the bell was cast as a quarter circle and the pressed in lobes cut out of it? Mine has quite sharp edges suggesting just that:
The intriguing thing, when you look closely, is that the suspension loop is at right angles to where you might expect it to be. I expected it to be parallel in its long axis with the flat metal, but instead it is at right angles on the one illustrated here and mine. Which indicates that it was hung on a horizontal wire perpendicular to the viewer, and this also ensures that the seam is at the back.
The other main type of rumbler bell mentioned in the linked article is this sort of spherical one:
Note the decorations on it, which in one case probably makes them more post-medieval. They are made of gunmetal or other variety of copper alloy.
Making some of them will be fiddly. I will need stone or bronze moulds of the right shape. Once you’ve carved the half spheres in each you need to make a ball of clay and sand within which is embedded the rumbling stone, and is held in place by twigs or suchlike, so that there is a gap all around the ball of clay and sand. Hence the circular holes in the bells.
You can see in this photo of the inside of the broken bell that it is rather rough, which to me increases the likelihood of the sand/ clay mix idea, although it might also be down to corrosion:
Of course I dare say you could try making such things using the lost wax technique, and maybe they were, although it would be a faff, quicker to use stone mould once you’ve made them. Medieval manufacturing was as much about speed and efficiency as our is today, although they didn’t tend to use such words. What I find more of in Biringuccio (page 213) is “The outcome of this art is dependent upon and subject ot many operations which, if they are not all carried out with great care and diligence and well observed throughout, convert the whole into nothing and the results become like its name [cast away].”
Later, discussing how to cast small objects in frames or wooden boxes, he uses the words “…for the sake of convenience… “, and “It is truly a quick and easy method.” (Pages 326 and 327 of the Dover paperback)
So, over the next few months I intend to try and make some of the long type of bell using the lost wax method. Carving stone for both types of bells will take a lot longer, so don’t wait up for it.